Vehicle occupant restraint systems having an actuatable restraining device are well known in the art. One particular type of actuatable restraining device includes an inflatable air bag mounted to inflate within the occupant compartment of the vehicle. The air bag has an associated, electrically actuatable igniter, referred to as a squib.
Such occupant restraint systems further include a crash sensor for sensing the occurrence of a vehicle crash condition and for providing an electrical signal indicative of the crash condition. When the crash sensor indicates that the vehicle is in a crash condition, an electric current of sufficient magnitude and duration is passed through the squib for the purpose of igniting the squib. The squib, when ignited, ignites a combustible gas generating composition and/or pierces a container of pressurized gas operatively coupled to the air bag, which results in inflation of the air bag.
Even if a vehicle is equipped with an air bag restraint system, it is not always desirable to inflate the air bag every time a crash condition occurs. Crash conditions are classified as either non-deployment crash conditions or deployment crash conditions. Non-deployment crash conditions are those for which the occupant seat belt alone provide adequate protection of the occupant. Deployment crash conditions are those for which deployment of the air bag is required to protect the occupant adequately. U.S. Pat. No. 5,073,860 provides an air bag restraint system including a crash detection arrangement that distinguishes between deployment and non-deployment crash conditions and controls deployment of the air bag in response to the determined type of vehicle crash condition.
Even if a vehicle is equipped with an air bag restraint system and a deployment crash condition occurs, it is still not desirable to deploy the air bag if certain occupant related conditions exist. Specifically, it is not desirable to deploy the air bag if an occupant is absent from a seat location associated with that air bag. Also, if an inanimate object is on the seat, it is not desirable to deploy the air bag during a vehicle deployment crash condition.
Moreover, it is desirable to control deployment of the air bag upon the occurrence of a deployment crash condition as a function of the occupant's position on the vehicle seat. It is desirable to control the inflation profile of the air bag and the timing of deployment dependent upon the occupant's position so as to maximize protection afforded by the air bag. If the air bag is capable of being aimed, it is desirable that the direction of deployment be controlled in response to the occupant's position. If the vehicle is equipped with a plurality of separately deployable air bags for each occupant, it is desirable that the control of the air bag deployments, e.g., which air bags are deployed and the timing of their deployment, be controlled in response to the sensed position of the occupant. If an occupant is completely out of position, it may be desirable that the air bag not be deployed at all. An occupant being out of position means that the occupant is not seated "properly" so that deployment of the air bag would enhance protection of the occupant during a deployment crash condition.
U.S. patent application Ser. No. 682,908, filed Apr. 9, 1991, now U.S. Pat. No. 5,232,243, discloses an air bag restraint system having sensors located in an occupant seat of the vehicle. These sensors detect whether an object in the seat is an inanimate or animate object. The system further determines whether an occupant is properly positioned in the seat. The air bag is deployed upon the occurrence of a vehicle deployment crash condition only if an animate occupant is determined to be present in the seat and if the occupant is properly positioned so that deployment of the air bag would enhance protection of the occupant.